Re: PG 16 draft release notes ready

From: Pavel Luzanov <p(dot)luzanov(at)postgrespro(dot)ru>
To: Bruce Momjian <bruce(at)momjian(dot)us>, Noah Misch <noah(at)leadboat(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>
Subject: Re: PG 16 draft release notes ready
Date: 2023-08-17 05:37:28
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On 17.08.2023 05:36, Bruce Momjian wrote:
> On Wed, Aug 9, 2023 at 08:35:21PM -0400, Bruce Momjian wrote:
>> On Sat, Aug 5, 2023 at 04:08:47PM -0700, Noah Misch wrote:
>>>> Author: Robert Haas <rhaas(at)postgresql(dot)org>
>>>> 2022-08-25 [e3ce2de09] Allow grant-level control of role inheritance behavior.
>>>> -->
>>>> <listitem>
>>>> <para>
>>>> Allow GRANT to control role inheritance behavior (Robert Haas)
>>>> </para>
>>>> <para>
>>>> By default, role inheritance is controlled by the inheritance status of the member role. The new GRANT clauses WITH INHERIT and WITH ADMIN can now override this.
>>>> </para>
>>>> </listitem>
>>>> <!--
>>>> Author: Robert Haas <rhaas(at)postgresql(dot)org>
>>>> 2023-01-10 [e5b8a4c09] Add new GUC createrole_self_grant.
>>>> Author: Daniel Gustafsson <dgustafsson(at)postgresql(dot)org>
>>>> 2023-02-22 [e00bc6c92] doc: Add default value of createrole_self_grant
>>>> -->
>>>> <listitem>
>>>> <para>
>>>> Allow roles that create other roles to automatically inherit the new role's rights or SET ROLE to the new role (Robert Haas, Shi Yu)
>>>> </para>
>>>> <para>
>>>> This is controlled by server variable createrole_self_grant.
>>>> </para>
>>>> </listitem>
>>> Similarly, v16 radically changes the CREATE ROLE ... WITH INHERIT clause. The
>>> clause used to "change the behavior of already-existing grants." Let's merge
>>> these two and move the combination to the incompatibilities section.
>> I need help with this. I don't understand how they can be combined, and
>> I don't understand the incompatibility text in commit e3ce2de09d:
>> If a GRANT does not specify WITH INHERIT, the behavior based on
>> whether the member role is marked INHERIT or NOINHERIT. This means
>> that if all roles are marked INHERIT or NOINHERIT before any role
>> grants are performed, the behavior is identical to what we had before;
>> otherwise, it's different, because ALTER ROLE [NO]INHERIT now only
>> changes the default behavior of future grants, and has no effect on
>> existing ones.
> I am waiting for an answer to this question, or can I assume the release
> notes are acceptable?

I can try to explain how I understand it myself.

In v15 and early, inheritance of granted to role privileges depends on
INHERIT attribute of a role:

create user alice;
grant pg_read_all_settings to alice;

By default privileges inherited:
\c - alice
show data_directory;
(1 row)

After disabling the INHERIT attribute, privileges are not inherited:

\c - postgres
alter role alice noinherit;

\c - alice
show data_directory;
ERROR:  must be superuser or have privileges of pg_read_all_settings to
examine "data_directory"

In v16 changing INHERIT attribute on alice role doesn't change
inheritance behavior of already granted roles.
If we repeat the example, Alice still inherits pg_read_all_settings
privileges after disabling the INHERIT attribute for the role.

Information for making decisions about role inheritance has been moved
from the role attribute to GRANT role TO role [WITH INHERIT|NOINHERIT]
command and can be viewed by the new \drg command:

                    List of role grants
 Role name |      Member of       |   Options    | Grantor
 alice     | pg_read_all_settings | INHERIT, SET | postgres
(1 row)

Changing the INHERIT attribute for a role now will affect (as the
default value) only future GRANT commands without an INHERIT clause.

Pavel Luzanov
Postgres Professional:

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